The Right Side

On the right side, the descending duodenum may be abnormally positioned posteriorly. Normally, the second portion of the duodenum descends immediately anterior to the medial half of the right kidney. In the right lateral projection during an upper gastrointestinal series, the descending duodenum projects anterior to the lumbar spine. With congenital absence or failure of ascent of the right kidney, the descending duodenum may occupy the area of the renal bed and project well over the lumbar spine (Figs. 9-47 and 9-48). Its course on a frontal radiograph appears normal.

Proximal jejunal loops may also occupy a similar position, filling in the renal fossa and coursing abnormally posteriorly (Figs. 9-47 and 9-48).

In right renal agenesis or ectopia, the posterior position ofjejunal loops within the renal bed might be most readily confused with a right paraduodenal her-

nia. The loops, however, do not possess the characteristic circular grouping, stasis, and dilatation; the identifiable afferent and efferent limbs; or the fixation and nondisplacement within an encapsulated hernial sac, despite multiple positions. Distinction is further made by arteriography. In agenesis of the right kidney, jejunal loops and their mesentery and vessels are deflected anterior to the superior mesenteric artery into the right flank. In a right paraduodenal hernia, jejunal loops and their mesentery and vessels pass through the fossa of Waldeyer posterior to the superior mesenteric artery into a hernial sac of the ascending mesocolon. Frontal projections alone thus show similar findings, with the jejunal arteries arising normally from the left side of the superior mesenteric artery and then coursing abruptly to the right to supply a group of small bowel loops in the right abdomen. Lateral projections during aortog-raphy or, more clearly, during selective superior mes-enteric arteriography readily differentiate between the two.

The posterior hepatic flexure of the colon may show characteristic posteromedial angulation, occupying the area of the right renal fossa21 (Figs. 9-49 and 9-50).

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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